The present invention relates to ground clamps and, more particularly, to ground adapters for use with C-clamps in connecting electrical cables to a ground object.
In order to complete an electrical circuit for enabling performance of electric arc welding and metal removing operations, it is necessary to connect one terminal of a welding machine (power supply) to ground potential. In electric arc welding operations, it is common to connect one terminal of the welding machine to an electrode while the remaining terminal is connected through a suitable adapter to a ground object, such as the workpiece. However, as extremely high currents, up to 3,000 amps are generated during the course of such operations, it is necessary to effect a secure connection between the ground object and electrical ground cable which connection does not produce excessive heat or significant voltage drops thereacross.
C-clamp devices have been used to connect electrical cables to a ground object. Previously, this connection has been effected by securing the cable to the body of the C-clamp such that upon tightening the spindle, a ground object is retained between a pad and foot portion of the C-clamp body. Another type of prior art device is shown in U.S. Pat. No. 2,420,895 wherein a special C-clamp and connecting lug are utilized. It has been found that prior art ground devices have suffered from the disadvantage of generating excessive amounts of heat as well as producing undesirable voltage drops simply due to the resistance of the ground device. Furthermore, prior art ground devices utilized with C-clamps have not been sufficiently flexible in that particular ground devices have been generally suitable only for a single sized C-clamp and have not been found suitable for use with a wide range of C-clamp sizes. This has been particularly true with respect to relatively large C-clamps which have correspondingly large feet or pads. Accordingly, prior art ground clamping devices have not proven effective in use with C-clamps of sizes required to retain relatively large ground objects or workpieces, e.g. 4-6 inches thick, in contact with a typical prior art ground lug or device. Therefore, it has been found that a clear need exists for a ground adapter useable with a wide variety of sizes of conventional C-clamps.